1. 14-1

2. Part Three
SOURCES AND
COLLECTION OF DATA
14-2
McGraw-Hill/Irwin © 2003 The McGraw-Hill Companies, Inc.,All Rights Reserved.

3. Chapter Fourteen
EXPERIMENTATION
14-3

4. Variables in Experiments
• Independent variables
• Dependent variables
14-4

5. Advantages of an Experiment?
• Researcher’s ability to manipulate the
independent variable
• Contamination from extraneous
variables can be controlled more
efficiently
• Convenience
• Cost
• Replication
14-5

6. Disadvantages of Experiments
• Artificiality of the laboratory
• Generalization from nonprobability
samples
• Larger budgets needed
• Restricted to problems of the present or
immediate future
• Ethical limits to manipulation of people
14-6

7. Experimentation Process
• Select relevant variables
• Specify the treatment levels
• Control the experimental environment
• Choose the experimental design
• Select and assign the participants
• Pilot-test, revise, and test
• Analyze the data
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8. Ways to Assign Subjects
• Random Assignment
• Matching Assignment
– Quota matrix
14-8

9. Does a Measure Accomplish
What it Claims?
• Internal validity
• External validity
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10. Threats to Internal Validity
• History • Selection
• Maturation • Statistical
• Testing Regression
• Instrumentation • Experimental
Mortality
14-10

11. Threats to External Validity
• The Reactivity of Testing on X
• Interaction of Selection and X
• Other Biasing Effects on X
– Artificial setting of testing
– Respondents knowledge of testing
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12. Experimental Designs
• Preexperimental designs
• True experimental designs
• Field experiments
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13. Design Symbols
X the introduction of an experimental
stimulus to the participant
0 a measure or observation activity
R an indication that sample units have
been randomly assigned
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14. Preexperimental Designs
• One-shot case study
• One-group pretest-posttest design
• Static group comparison
14-14

15. True Experimental Designs
• Pretest-posttest control group design
• Posttest-only control group design
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16. Operational Extensions of True Designs
• Completely randomized designs
• Randomized block design
• Latin square
• Factorial design
• Covariance analysis
14-16

17. Field Experiments:
Quasi- or Semi-Experiments
• Non Equivalent Control Group Design
• Separate Sample Pretest-Posttest
Design
• Group Time Series Design
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